This command enables factory image generation for Cameo boards. On
upgrade the vendor firmware will check the size of the provided image
and if a specific string is located at the end of the binary.
cameo-factory will generate an image that the vendor firmware accepts.
Tested on a D-Link DIR-825 C1 with vendor firmwares 3.01 and 3.04.
Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>